Nuclear War

Nuclear war has but a brief history. In 1945 two low-yield weapons were used against Japanese cities, resulting in the surrender of Japan to the Allies. Nuclear deterrence has had a richer history, but much of this history has little relevance to matters of current importance. This article will therefore focus on the present and prospective consequences of the existence of nuclear weapons.

As context for this discussion, it is important to point out the many factors in the international situation that remain unchanged since 1945. First —and perhaps most important—in spite of international legal institutions that are effective and valuable in a wide range of ordinary situations, crises continue to arise in which each nation becomes the judge of its own cause and of the methods and intensity with which it will seek to advance its interests. Thus, international conflicts have always been prone to “escalation” (a “qualitative” increase in the intensity or level of conflict or violence, perhaps occurring inadvertently, perhaps resulting from a conscious competition in risk taking or even from a deliberate increase in the use of force). I emphasize the pervasiveness of the escalation concept, which implies that in most conflicts there will be force that remains unused. Nuclear weapons have increased the amount of force that tends to remain unused but are not themselves responsible for the possibility that low levels of violence will escalate to medium levels or even very large-scale destruction; that possibility has almost always been present.

Moreover, it is still most unlikely that a thermonuclear war would mean the “end of history,” not because it is technologically impossible to end human history by the use of nuclear explosives but simply because, at this writing (i.e., in 1967), even the superpowers have not procured the kinds of weapons systems that could—in a realistic situation—bring about such a result; nor are they likely to procure such systems. Even if a thermonuclear war were actually fought today by the existing powers, and even if it were fought with the utmost ferocity and lack of control, such a war would be likely to end with the Southern Hemisphere and large portions of Asia largely undamaged. Nor would the survivors in the Northern Hemisphere be likely “to envy the dead.” Recuperation is extremely likely, and, although it is true that according to the best scientific estimates, the postwar environment might be more hostile to human life for many years, objective studies also indicate that this environment would not be so hostile as to preclude, at least in the long run, decent and useful lives for the survivors and their descendants. Indeed, what evidence there is suggests that relatively normal and happy lives would not be impossible even under the harsh conditions that might prevail after a nuclear war, in spite of the personal and social traumas that would have been experienced.

Of course, to say that a nation can survive a thermonuclear war is not to say that all the problems—military, social, political, economic, and medical—that would arise from a thermonuclear war can be handled. Would the social organism fall apart completely—that is, die in some sense— as a result of the tremendous shock it would receive from a large thermonuclear war? Obviously there is no way of being certain. However, insofar as there are historical examples to study (and some of them are close to thermonuclear wars in intensity, e.g., the devastation of Germany and the Soviet Union in World War n), they provide evidence that people can and do rise to the occasion (Kahn 1962).

The age-old role of bargaining in war (e.g., working on the enemy’s mind rather than on his body or resources) may be increased rather than decreased both before and after a nuclear attack. Deterrence is, in effect, a form of bargaining and could occur not only before but also during and after a war (including a war caused by a failure of deterrence)—i.e., even if deterrence fails and war occurs, each side is likely to want to withhold some weapons in order to be able to threaten the enemy and may be anxious to settle the war while the other side still has not used its withheld weapons. The possibility of technological, tactical, or strategic surprise also still exists. Despite current beliefs in stability, “Pearl Harbors” and “Munichs” remain possible (i.e., deterrence may not necessarily favor the defensive or status quo side); thus, those who take risks may find that their gamble has not failed. Finally, even though countries will be less likely to risk war, in some ways surprises and “unexpected” victories are more likely in a nuclear war era (i.e., war could occur as a result of correct calculations as well as by miscalculation).

While mutual destruction and Pyrrhic victories can occur, such possibilities have been with us at least as long as recorded history, and the fact that they could occur days or even hours after the start of hostilities, rather than after weeks, months, or years, does not necessarily change the basic issues and situations that have arisen in the past. Thus, history may repeat itself in the thermonuclear era, which could experience successful wars and aggressions as well as mutually destructive ones.

The most important way in which the thermonuclear era differs from previous eras is that the changes in the available technology have, by themselves, been large enough to change the strategic situation and the character of international relations. This has resulted both in posing very different strategic issues and in changing the answers to old issues. Thus, in this period U.S. strategic weaponry has changed (or is changing) from B-50 bombers to B-36 bombers, to B-47s, and finally to B-52s; and from Atlas and Titan intercontinental ballistic missiles to early-model Minuteman and Polaris, and now to Minuteman-2s and Polaris A-3s. These changes have produced enormous differences in the effectiveness of the forces. Even the change from Minuteman-1 to Minuteman-2 can by itself increase the effectiveness of a force by a large factor (doubling—or perhaps redoubling several times—the size of a nation’s missile forces), to the extent of altering the outcome of a war.

However, since all these changes have occurred without being tested in battle, one can question whether their full significance has even been absorbed intellectually, much less in plans and programs.

Indeed, it is clear that in many respects the two superpowers, and certainly the other nations, have failed to understand these rapidly changing interactions between technology and doctrine. We can (with some violence to the subtleties, and viewing the subject from the viewpoint of the U.S. government) consider the two postwar decades as four five-year eras characterized as follows:

1946-1950: Early fission and bomber era; entry of Soviet Union into nuclear club.

In the early nuclear bomber era, the strategic balance was one-sided, for the Soviets did not test their first weapon until February 1949. However, the United States had not produced very many nuclear bombs, and it is doubtful that the U.S. strategic forces could have had anything like the decisive impact on a war that was popularly supposed—indeed, these forces might have done less damage to a Soviet war effort than the Germans did in World War n by invading and occupying Soviet territory.

By the early 1950s the United States had substantially increased its forces, but the Russians had scarcely begun to procure intercontinental bombers. They had a rather large force of medium bombers of the TU-4 (similar to the B-29) and Badger (like the B-47) types, but it now seems clear that both of these aircraft were designed and procured for European rather than intercontinental missions—although at the time no one in the United States or Europe seemed to realize this. Although thermonuclear weapons had been tested, the military stockpiles consisted almost wholly of kiloton bombs.

Despite slow means of delivery (bombers) and relatively low-yield warheads, both U.S. and Soviet forces were almost incredibly vulnerable to surprise attack. At the beginning of the period all U.S. strategic forces were located at a dozen bases. Hours, perhaps days, would have been required to evacuate them and days, perhaps weeks, of warning would have been necessary for them to be able to mount effective combat operations. Nuclear weapons were stored in a relatively vulnerable configuration (at first in one building and then in two). In the early part of this period, almost no one seems to have understood the subtleties of the problem of vulnerability. Active air defense was deployed to protect cities and nuclear research centers like Oak Ridge, Tennessee, and Hanford, Washington. Strategic Air Command bases were left unguarded, on the theory that no one would waste nuclear weapons on military bases. By the middle and end of the period, senior officers in the U.S. Air Force understood vulnerability somewhat but did not believe (it now seems correctly) that the Soviets had much actual operational strategic capability for a surprise attack.

By the late 1950s, third- and fourth-generation nuclear weapons had been procured by the United States and a large spectrum of such weapons was available to the U.S. forces, from small (“suitcase”) to multimegaton bombs. U.S. military planners and decision makers began to think of thermonuclear weapons as relatively inexpensive, but the Soviets still did not. However, the problems of vulnerability were still inadequately appreciated; in fact, by the end of the period there was much discussion of the existence of a “missile gap.” While the U.S. government conceded the existence of such a gap—and in fact was responsible for disseminating the estimates which gave it plausibility—it simultaneously argued there was no “deterrence gap,” since the five hundred missiles which U.S. intelligence attributed to the Soviet Union would have been unable to do as much damage as the two thousand bombers that the United States possessed. Congressional testimony and other documents disclose that almost none of the top civilian officials and relatively few scholars and journalists understood that these five hundred Soviet missiles, if they existed, could probably have destroyed the two thousand American bombers on the ground in a surprise attack (but see Wohlstetter 1959; Kahn 1960).

By the early 1960s the United States, at least, was well into the missile era, and almost everybody interested in such problems understood the distinction between “first-strike” and “second-strike” tactics, forces, and postures. However, according to the 1963 testimony of Defense Secretary Robert McNamara, the Soviets had not yet hardened and dispersed their missile forces, although it was expected that they would do so by the late 1960s. In the early 1960s some of the doctrinal lags of the late 1950s were revealed. For example, it was disclosed that the more important half of the U.S. Semi-automatic Ground Environment Air Defense System, the part designed to control the air battle in defense of strategic centers on the American east coast, west coast, and Canadian border, was located on Strategic Air Command (SAC) bases and thus was almost certain to be destroyed or disabled in any war in which Soviet missiles were successfully launched at these SAC bases. Similar mistakes in both installations and weapons systems occurred elsewhere. As a result, there was tremendous concern about vulnerability and emphasis on such problems as “reciprocal fear of surprise attack” (expressed in terms of “gun duel” models of a strategic confrontation in which the side which gets off a “shot” first may escape all retaliation).

By the end of this period the United States had begun to digest not only the preattack implications of two-way deterrence but also the possibility of intrawar or postattack deterrence, and therefore the need for restraint in the threat and use of force even after hostilities have begun. This resulted in the so-called controlled-response doctrine (Kahn 1960, pp. 171-175) and such policy statements as the one by Secretary McNamara that “principal military objectives in the event of a nuclear war stemming from a major attack on the Alliance, should be the destruction of the enemy’s military forces, not of his civilian population”(New York Times, June 17, 1962, pp. 26-27) and the statement of President Johnson in his defense message to the 89th Congress that “our military forces must be so organized and directed that they can be used in a measured, controlled, and deliberate way as a versatile instrument to support our foreign policy” (1965, p. 825).

Despite these statements, however, it becomes quite clear from other statements that both Secretary McNamara and President Johnson remained doubtful about the feasibility, likelihood, or even possibility of a controlled response in a major war. Moreover, there is little indication that the United States has thoroughly organized its forces (not to speak of the NATO forces) around these concepts.

The change from kiloton to megaton weapons in the early 1950s was, in some ways, as significant as the change from high-explosive to kiloton weapons in the mid-1940s. Until megaton weapons became available, it was unlikely that the U.S. Strategic Air Command could have done as much physical damage to the Soviet Union’s war effort as was actually accomplished by the German army in World War n. In the mid-1960s, in the multimegaton era, potential destruction from a thermonuclear war is almost incredibly large. The duration of an “all-out” war against city targets is now likely to be closer to a minimum of 30 minutes than to a maximum of 30 days. Analysts no longer ask “What is destroyed?” but “What is left?” What has also become apparent, loose rhetoric to the contrary, is that thermonuclear wars may come in many sizes and shapes. The analysts must, consequently, examine and estimate a large number of effects in a wide range of situations.

First, prewar tactics and strategy, which may make an enormous difference to the outcome, must be studied. Then the immediate effects of blast and “prompt” gamma and thermal radiation must be examined, as well as the subsequent effects of primary and secondary fires and of fallout radiation during the first week or two. If the war has involved widespread targeting of civilian areas, there are problems of human survival, of radioactivity, and of damage to the physical environment, and problems of economic and social disorganization. These require consideration of immediate repair and “patch-up,” and economic and social reorganization and recuperation (problems which so far have hardly been dealt with, despite many millions of dollars spent on research in these areas). Even in a controlled thermonuclear war the likely rate of economic and social recuperation (assuming the recuperation efforts themselves have been successfully launched) may be very different from those which would follow even a very destructive conventional war. There are also long-term environmental problems, including the medical aftereffects of radiation on exposed survivors. Finally, account must be taken of the genetic effects of radiation and long-range changes in the physical environment resulting from widespread radiation damage to plants and animals, large-scale fires, floods, possibly genetic changes in flora and fauna, and even weather changes.

Many of these questions are unprecedented; all are complex; and almost all tend to arouse “openended” fears. But in some ways the appearance of total uncertainty on these issues is misleading, since the results of thermonuclear war, particularly the destruction of enemy weapons and, to some degree, cities, as well as many physical aftereffects, are easier to calculate than are the results of the clash of two land armies fighting a conventional war. However, the lack of experience in such wars, and the absolute necessity for making and relying on decisions and analyses made in advance, means that, from a decision-making point of view, the situation is much more complex and uncertain. Also, while one can often make relatively precise estimates about the probability that something will be destroyed by some specific mechanism, it is often impossible to make precise statements that something has survived all the ways in which it could be destroyed.

One result of the potential increase in destructiveness combined with confusing complexities and uncertainties has been a major change in attitudes toward war. Such phrases as “absolute weapon” (doomsday machine), “balance of terror,” “live together or die together,” and “war is unthinkable” (or impossible or obsolete) illustrate widely held and widely expressed attitudes and beliefs. Not only is such total destruction hard to visualize, but it leads to the feeling that the deterrence of war, or even of the threat of war, is a simple and logical consequence of the existence of nuclear weapons.

The total destruction or “mutual homicide” interpretation of thermonuclear war has other comforting aspects. If it be granted that each side can utterly and reliably destroy the other, then expensive preparations to reduce casualties, lessen damage, and facilitate postwar recuperation are useless. Can we not spare ourselves the financial burden of such preparations? This logic has sometimes been carried further, to argue that if modern weapons are so enormously destructive, then only a few are needed to deter the enemy. War can be deterred with much smaller forces than in the past; and we certainly don’t need larger ones. Most influential of all of these arguments is that if destruction is always total and automatic, we need not spend time and energy worrying about details, comparison of risk, etc.

All of the above has led to a well-articulated and explicit dependence on deterrence—on dissuasion through terror—and the belief that the major role of a nuclear force is that of a deterrent and bargaining tool. As President John F. Kennedy said on March 28, 1961, in his special message to the Congress on the defense budget:

The primary purpose of our arms is peace, not war—to make certain that they will never have to be used—to deter all wars, general or limited, nuclear or conventional, large or small—to convince all potential aggressors that any attack would be futile—to provide backing for diplomatic settlement of disputes—to insure the adequacy of our bargaining power for an end to the arms race. (New York Times, March 29, 1961 pp. 16, 17)

Whether based on objective capabilities or “resolve,” the concept and use of deterrence are not new. However, today there is almost total emphasis on mutual terror and destruction—that is, the countervailing power does not emphasize its ability to negate the acts of the aggressive or active power, or to destroy or block his forces militarily, as in the past, but emphasizes instead its ability to harm the population, resources, or property of the opposing power. An explicit distinction is made today between deterrence and what is sometimes called denial (or defense), which is the physical prevention or alleviation of an action (as opposed to a “psychological” prevention, based mainly upon the threat of pain or destruction of other values). The relationship between deterrence and denial—the various ways in which they can reinforce or conflict with each other—has become the subject of much discussion (e.g., Kaufmann 1956; Kahn I960; 1962; Schelling I960; 1966).

Deterrence is, of course, a complicated relationship, and in trying to analyze deterrence situations, one may elaborate on Raymond Aron’s well-known questions by asking:... Who deters, influences, coerces or blocks whom from what actions (alternatives), by what threats and counteractions in what situations and contexts, in the face of what counterthreats and counter-counteractions?... and why does he do it? .. .

One can group the italicized variables into three groups: (1) political (who, whom, and why); (2) scenario (alternatives, situations, and context); and (3) military (actions, threats [or counteractions], and counterthreats [or counter-counteractions]). While most discussions of thermonuclear war generally emphasize only one or another of the above sets of variables, all three sets must be considered in an integrated way. (Only two works seem to have attempted this: Kissinger 1957; Strausz-Hupe et al. 1959.) Failure to do so constitutes a major source of misunderstandings about deterrence.

It is important to distinguish between what is sometimes called “passive” and “active” deterrence. “Passive” deterrence refers to a situation in which a nation has been so provoked (perhaps by a direct attack on its population) that the response is almost automatic. “Active” deterrence applies to a situation in which the “proper” response to provocation is clearly further escalation (perhaps one’s ally has been struck). In this situation it takes an act of will to respond. Rather than being an automatic act of revenge, the response may start a sequence leading to one’s own destruction.

It is also a mistake to treat deterrence as an either/or situation, instead of considering degrees of deterrence. In most situations one could usefully distinguish at least six levels of deterrence between the United States and the Soviet Union (Kahn 1965, pp. 277-280):

(1) Minimum (or low-level): (a) deterrence by uncertainty (including the use of dire but unbelievable threats as a declaratory policy but preemptive or preventive accommodation tactics as an action policy); (b) deterrence by threshold; (c) deterrence by taboo.

(6) Near absolute (or stark): reliable ability to threaten overkill by a factor greater than 2, so that no miscalculation or wishful thinking could confuse the potential attacker.

Although the above scale leaves out most of the subtleties associated with, for example, credibility issues, it correctly implies that there is a broad range of circumstances in which even a minimum deterrent might work and that there are circumstances in which the most stark deterrent might fail. The scale also suggests that the question “How much deterrence does a nation need?” cannot be answered simply by “As much as possible.” Rather, a range of scenarios, asking the whowhom-why kind of question not discussed here, must be examined, and, most important of all, the degree of assurance necessary for various situations must be weighed against the various costs of going higher on the scale of deterrence.

Deterrence clearly involves dissuasion by use of threat of varying degrees and kinds of terror, which in turn assumes that the deterree (and even the deterrer) possesses some degree of rationality— but usually very little: about as much as is demonstrated by a child who has learned not to burn himself or climb out of windows. Nevertheless, the emphasis on terror and rationality raises much apprehension, particularly among members of the peace groups but also among decision makers and analysts generally. This is not only because subtle and misleading situations can arise but also because many people feel, often reasoning from the psychology of the neurotic and psychologically disturbed, that threats and terror may attract rather than repel and that rationality is thus a weak reed on which to rest our hopes for preventing thermonuclear war. One can, however, fully share these apprehensions and still feel that deterrence is, for the time being, the safest and most moral alternative available. But while apprehensions are often exaggerated, even the most optimistic may still wish some protection against the failure of deterrence and may work to improve and eventually to reform the deterrent system. [SeeDeterrence.]

By the late 1960s at least five or six countries should have reached India’s position in 1965, i.e., that of having completed almost all research necessary to assemble and test a nuclear device but having stopped short of developing a “working” model (a matter of perhaps less than a year and less than a $1 million cost) because of governmental reluctance to authorize this final step. This situation may become typical, and it would not surprise most scholars if there were no new entries into the “nuclear club” during the next decade. As of 1966, there have been no public entries into the nuclear race for more than ten years: China and France made and announced their initial decisions to become nuclear powers before this period.

In terms of delivery systems, the late 1960s will be the early missile era, in that most nations will not have achieved the kind of capabilities that the United States will possess. The United States, in turn, will probably have entered the mature missile era, since at least some U.S. missiles will be cheap, reliable, and relatively small in size; will possess great range, good accuracy, and reasonable payload capability; and will be capable of complicated or sophisticated tactical performance.

The cost of a simple Minuteman missile system is likely to be something between $1 and $2 million a year per missile to buy and maintain, as long as there is reasonable access to production and operating techniques comparable to those of the United States. These costs are likely to apply to missile systems with at least hundreds but not necessarily thousands of missiles. Thus, on the basis of U.S. costs, any nation will be able to have, say, a 500missile Minuteman-type strategic force for a budget of between $500 million and $1 billion a year.

There are many who now believe that the kind of revolutionary technological changes that have occurred since 1945 will, for practical purposes, have come to a stop. This belief is usually based on various versions of overkill theories and the conviction that nuclear “stalemates” are not susceptible to breakthroughs in technology. The argument runs as follows:

From 1965 on, or soon afterward, both the United States and the Soviet Union will be able to inflict unacceptable damage on each other under all circumstances, using more or less existing, or moderately improved, systems. Thus, if one nation or the other provides a new way to damage or destroy its potential opponent’s civilian society, the deterrent equation is not affected. For this reason the many possible technological improvements in offensive power (against civilians) will not affect international relations. The same will probably be true in the unlikely event that there are major improvements in defense (or counterforce) capability. The current stalemate is at a high enough level so that each nation will still be able to inflict unacceptable damage in retaliation, even if its capability is cut by a large factor. This will be true practically, even if it is not true theoretically, because if one side does invent and procure some breakthrough, it cannot rely on the system’s working properly (perfectly?) the first time it is put to the test and will therefore be “deterred by uncertainty,” and deterred almost as effectively as if the deterrence rested on objective capabilities and calculations. Therefore, at least in the area of central war (i.e., nuclear war involving the homelands of the major powers), there is little or no interest in examining technology with the same intensity that was necessary in the last two decades.

Even though it ignores many important issues, this argument is persuasive and may prove to be practically correct as far as the politics of U.S. Soviet confrontations are concerned—although both countries will still work at improving their forces, and such improvements might make a dramatic difference in the outcome if deterrence ever failed. In any case, as Figure 1 shows, budgets for central war forces have been declining over the years (in the late 1950s the total budget was probably close to $15 billion). The data suggest either that thermonuclear war is getting much less expensive or that the United States is becoming satisfied with much less capability (actually, both effects are occurring).

The argument leaves open the question of a confrontation between one of these central superpowers and an nth country or a confrontation between nth countries. In these situations many of the points made above lose much of their force. Although such lesser confrontations do not seem to raise the question of the future of the entire world as immediately and intensely as U.S.-Soviet ones, the most significant technological arms race will probably go on “outside” the direct confrontation of the two superpowers (unless, of course, the superpowers go in for elaborate arms control or active and passive defense, in which case technology will again make a great difference). There will in any case be a widespread distribution of longrange missile technology using both solid and liquid fuels. Missile technology will proliferate more rapidly than weapons technology because of lesser secrecy, due, in part, to the much greater application of missile technology to normal peacetime research and engineering.

The strategic situation will probably be very much affected by whether or not the United States and/or the Soviet Union allocate sufficient resources to active and passive defenses to keep ahead of the later entries into the nuclear club. If either spends, say, $5-$ 10 billion a year in this area, they will probably preserve an important, perhaps overwhelming, strategic asymmetry. If they do not do this, and the likelihood is that they

* Includes procurement, maintenance, and operation of strategic offense and active and passive defense of the United States, but no R & D programs.

will not, the situation will be closer to that illustrated by an example drawn from the American West, where the six-shooter was the great equalizer, and there will be a lesser tendency to differentiate between superpowers and great powers.

If there is widespread proliferation, the situation will doubtless be quite dangerous; but despite the obvious dangers, it is not likely that a war between two small or medium powers, or even large powers, would trigger an orgy of destruction in which every power joins. In a world of nuclear proliferation the concept of controlled response will be firmly fixed in everybody’s mind, and it is inconceivable that many, if indeed any, nations will want to enlarge a nuclear war in which they are not directly and vitally involved—and perhaps not even then. It may even be that a nuclear war may occur between two smaller powers in which both sides are wiped out, or even in which one side “wins” but at a cost which results in a sobering, not to say chilling, effect on all. Most dangerous of all, one power may win clearly and easily, and succeed in keeping its winnings. This might be a great spur both to further proliferation and to risk taking by some of the more aggressive nuclear powers.

By the late 1970s, in short, the technological and economic possibilities for proliferation will be such that unless there are extreme implicit or explicit constraints against it, a widespread or even explosive proliferation can be expected. By the 1980s we will be either in the postnuclear era or in what may be thought of as the mature nuclear era. That is, we will be living either in a world in which large numbers of powers have nuclear weapons or in a world in which nuclear weapons have been effectively controlled.

Parallel to the acceleration of the advances in modern technology in the twentieth century, there has been a growing feeling that technological leaps forward (rather than morality) have made war unacceptable. However, another reason why war is “unacceptable” should also be noted: the existence of a “peace of satisfaction” (Aron 1962). To illustrate this phrase, consider Latin America today, where for the last two decades there has been almost no major threat of war. The explanation obviously has nothing to do with nuclear weapons. Yet if these nations possessed such weapons, almost everyone would ascribe the relative peace of the period to the existence and effectiveness of nuclear deterrence. Similarly, most of the large nations in the world today are deterred—but even more, they are defensive, prudent, and in large part supporters of the status quo. Nevertheless, nuclear weapons do pose the possibility of mutual destruction and thus raise the question of war’s practicality or usefulness as a social institution in an entirely different way than does “conventional” war. The answers to this question reflect at least three common attitudes toward nuclear weapons:

(1) An unqualified rejection, which also includes a rejection of deterrence —i.e., it is argued that since deterrence can fail, we must move to a situation in which the weapons themselves no longer exist. This condition would doubtless be desirable, but it is difficult to see how it is likely to be achieved without much more peaceful evolution—or crises or wars—than seems likely in the immediate future. It seems unlikely that the threat of nuclear war will be “settled” through peaceful evolution and international cooperation in the next decade or so, although these may help facilitate the “eventual settlement.”

(2) A more common attitude of qualified rejection of nuclear weapons as useful for any purpose except to deter their use by others. All the various kinds of finite deterrence strategies and basic deterrence strategies express this attitude, and little or no preparation is advocated for alleviating the consequences if deterrence fails.

(3) A qualified acceptance of nuclear weapons or resignation to their continued existence and possible use. Acknowledging all of the points made earlier on ways in which the world situation has not changed, some of these “acceptors” believe in a self-defeating prophecy—i.e., that deterrence will be much more likely to fail if too many people believe that “war is unthinkable.” Some of this group also argue that even during a war there might be deterrence of many actions and thus some degree of control. Few of this group would argue that such intrawar deterrence can be relied on. All believe, however, that the likelihood of maintaining control, even after nuclear weapons have been used, is so high that attempts should be made to exploit it. Finally, there are those who wish also to support a bargaining position, or to hedge, against a loss of control, by having some active and passive defense and some offensive counterforce ability.

Whatever the attitude about the feasibility of various solutions, hardly anyone considers the arms race or large-scale war useful in international relations. President Kennedy expressed, in two aphorisms, what seems to be the consensus of mankind. The first was in his UN address of September 25, 1961: “The weapons of war must be abolished before they abolish us”; the second, in his budget message of January 18, 1962, was that we must “retain for ourselves a choice other than a nuclear holocaust or retreat.” The first statement counsels us to change the current international system; the second, to maneuver successfully within it. The dilemma of the nuclear age is usually posed by arguing that these two imperatives are both valid and mutually exclusive. And indeed, although it may prove impossible to change the current system until after it has failed conspicuously and perhaps disastrously, the second imperative could also help to deal with the first one.

In any case, we seem, for the time being, to be succeeding in avoiding both disastrous appeasement and withdrawal or escalation to catastrophic levels. To hope that this success can be perpetuated is to hope for more than just the accurate and detailed awareness of the need to maintain military and political strength while limiting the new potential for unprecedentedly rapid, long-range, and widespread destructiveness. These efforts, of course, are more likely to avert eruption of a cataclysmic war or appeasement only if there is understanding of all the dangers and options. In addition, increased awareness of all the issues may motivate sufficient international reform and simultaneously constrain all national decision makers to exhibit a consistently high degree of caution, reasonableness, and restraint in their dealings with one another, whether in peace or in limited war. The issue is, of course, still open.

Strausz-Hupe, Robert et al. 1959 Protracted Conflict. New York: Harper. → A paperback edition was published in 1963.

Tucker, Robert W. 1960 The Just War: A Study in Contemporary American Doctrine. Baltimore: Johns Hopkins Press.

U.S. Air Force Academy, Department of Political Science 1965 American Defense Policy. Prepared by Wesley W. Posvar and others. Baltimore: Johns Hopkins Press.

U.S. Armed Forces Special Weapons Project (1950) 1962 The Effects of Nuclear Weapons. Edited by Samuel Glasston. Washington: U.S. Atomic Energy Commission. → First published as The Effects of Atomic Weapons.

Wohlstetter, Albert (1961) 1965 Nuclear Sharing: NATO and the N + 1 Country. Pages 186-212 in Henry A. Kissinger (editor), Problems of National Strategy: A Book of Readings. New York: Praeger. → First published in Volume 39 of Foreign Affairs.

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Nuclear Weapons

Encyclopedia of Espionage, Intelligence, and Security
COPYRIGHT 2004 The Gale Group Inc.

Nuclear Weapons

█ LARRY GILMAN/

K. LEE LERNER/

DEAN ALLEN HAYCOCK

Nuclear weapons are explosive devices that utilize the processes of fission and fusion to release nuclear energy. An individual nuclear device may have an explosive force equivalent to millions of tons (megatons) of trinitrotoluene (TNT, the chemical explosive traditionally used for such comparisons), more than enough to completely destroy a large city. The destructive power of nuclear weapons derives from the core of the atom, the nucleus. One type of nuclear weapon, the fission bomb, uses the energy released when nuclei of heavy elements, such as plutonium, fission or split apart. A second even more powerful type of nuclear weapon, the fusion or hydrogen bomb, uses the energy released when nuclei of hydrogen are forced to fuse (join together).

Nuclear devices have been fashioned into weapons of many shapes with many purposes. Bombs can be dropped from airplanes; warheads can be delivered by missiles launched from land, air, or sea; artillery shells can be fired from cannons; mines can be placed on the land and in the sea. Some nuclear weapons are small enough to destroy only a portion of a battlefield; others, as already mentioned, are large enough to destroy entire cities and more.

Unlike chemical explosives, nuclear weapons have had no peacetime uses, although in the 1950s the U.S. government briefly considered using them to blast artificial harbors in the Alaskan coastline. They are possessed by a number of nations, including the United States, France, Great Britain, China, India, Israel, Pakistan, and the Russian Federation along with several former Soviet Republics. Iran and North Korea, among other nations, are interested in building them. Since nuclear weapons were invented during World War II, they have been used only twice, both times against cities in Japan by the United States.

Development of nuclear weapons. German physicist Albert Einstein (1879–1955) did not know it at the time, but when he published his Special Theory of Relativity in 1905 he provided the world with the basic information needed to build nuclear weapons. Einstein said that the amount of matter of an object (i.e., its mass) is equivalent to a specific amount of energy. The exact amount of energy in an object equals its mass multiplied by the square of the speed of light. The speed of light is large—186,282 miles per second (300,000 km/sec)—so even a small piece of matter contains a vast amount of energy. A baseball-size sample of uranium-235, for example, can explode with as much energy as 20,000 tons of TNT—and this involves the conversion of only a tiny fraction of the uranium's mass into energy. One pound of explosive material in a fission weapon is approximately 100,000 times as powerful as one pound of TNT.

As World War II approached, two German chemists, Fritz Strassmann (1902–1980) and Otto Hahn (1879–1968), pointed a stream of neutrons at a sample of uranium and succeeded in splitting the nuclei of some of its atoms. This splitting of nuclei is termed nuclear fission. The energy released through nuclear fission was the source of power for the first atomic bomb, which was built in the United States by a large team of scientists led by U.S. physicist J. Oppenheimer (1904–1967). This secret research and development program was termed the Manhattan Project.

The first atomic bomb was detonated in a test at Alamogordo, New Mexico, on July 16, 1945. Three weeks later, on August 6, a bomber named Enola Gay dropped a four-ton atomic bomb containing 12 lb (5.4 kg) of uranium-235 on the Japanese city of Hiroshima. Seventy thousand people died as a direct result of the blast. Within two months, nearly twice that many were dead from blast injuries and radiation. Three days later, on August 9, a bomb containing several pounds of plutonium was dropped on Nagasaki. Thirty thousand people died in the seconds following the explosion, and more later. The Japanese surrendered the next day, ending World War II.

These first nuclear weapons were atomic bombs or A-bombs. They depended on the energy produced by nuclear fission for their destructive power. However, scientists like U.S. physicist Edward Teller (1908–) knew even before the first atomic bomb exploded that the fission weapons could be used to create an even more powerful explosive, now called a thermonuclear device, hydrogen bomb, or H-bomb. This weapon gets it power from the energy released when atoms of the hydrogen isotopes deuterium or tritium are forced together, a process called nuclear fusion. Starting a nuclear fusion reaction is even more complicated than setting off a fission atomic bomb; it requires such heat to initiate it that a fission bomb is used as a detonator to explode the fusion bomb. The United States tested the first hydrogen bomb on November 1, 1952. It exploded with the force of 10.4 megatons (millions of tons of TNT equivalent). Three years later, the Soviet Union exploded a similar device.

For the next 40 years, the United States, with its allies, and the former Soviet Union, with its allies, raced to build more nuclear weapons, with each side producing tens of thousands. The end of the cold war and the breakup of the Soviet Union in the early 1990s led to the elimination of a significant number of nuclear weapons; however, the U.S. and Russia still possess many thousands of nuclear weapons.

The physics and mechanics of nuclear weapons. Conventional, chemical explosives get their power from the rapid rearrangement of chemical bonds, the links between atoms made by sharing electrons. In chemical explosives, atoms dissociate from other atoms and form new associations; this releases energy, but the atoms themselves do not change. Nuclear weapons are based on an entirely different principle. They derive their explosive power from changes in the structure of the atom itself, specifically, in the core of the atom, its nucleus.

Atomic bombs use the energy released when nuclei of heavy elements split apart or fission. Uranium and plutonium are the two elements that can be used as fuel for this type of weapon. When nuclei of these atoms are struck with rapidly moving neutrons, they are broken into two pieces nearly equal in size. They also release more neutrons, which split more nuclei. This is called a chain reaction. If enough atomic nuclei split they will release enough neutrons to ensure that all the nuclei of all the atoms in a sample will be split. Enormous amounts of energy are then released in a fraction of a second. This release of energy is the power behind the atomic bomb.

Uranium and plutonium are termed fissile materials because they can support a fission chain reaction if enough material is concentrated in one place. Too small a sample would not generate enough neutrons to keep the fission process going; for example, a one-pound (.45-kg) sample of uranium-235, a sample about the size of a ping-pong ball, is not large enough to support a chain reaction. The atomic bombs used in World War II proved that 12 or so pounds (about 5.5 kg) of fissile material, larger than a ping-pong ball but still small enough to fit into your hand, is enough to maintain a chain reaction. The smallest amount of material that can support a chain reaction is called the critical mass.

The instant enough bomb material is gathered together into a critical mass, a chain reaction begins. (At higher density, less mass is required.) This means that fissile material cannot be assembled in a critical mass until it is meant to explode. Therefore, the sample of uranium or plutonium in an atomic bomb is separated into several pieces, each of which is below critical mass. To set the bomb off, the separated pieces of bomb material are rammed together to create a critical mass. One design for creating a critical mass involves firing a subcritical "bullet" of fissile material into a subcritical "target" of fissile material. Together, the bullet and the target create a critical mass that starts a chain reaction leading to a nuclear explosion.

A different design was used to detonate the bomb dropped on Nagasaki. Plutonium was stored in one large but subcritical mass. It was compressed to a critical density by means of surrounding chemical explosives. When the chemical explosive detonated, the blast forced the bomb material into a density that reached criticality. In either type of design, once criticality is reached the explosion follows in a millionth of a second.

In order for nuclear fission to occur, a bomb must use heavy atoms for fuel. Heavy atoms have many nucleons—neutrons and protons—in their nuclei. When these heavy nuclei split apart they release energy (and neutrons, which may cause nearby heavy nuclei to split apart also). Another more powerful type of nuclear weapon uses forms of hydrogen as fuel. Hydrogen has few subatomic particles in its nuclei—usually only a proton, but the isotope deuterium has a proton plus a neutron, while the isotope tritium has a proton plus two neutrons. Instead of being split apart, these light atomic nuclei are forced together in high-speed collisions, a process called nuclear fusion. Energy is released when hydrogen nuclei fuse, forming helium. Fusion only occurs at temperatures of millions of degrees, such as exist in the hearts of stars. (The sun and other stars generate their energy primarily by fusing hydrogen into helium.) On Earth only an atomic bomb can raise kilograms of material to such a temperature, which is why atomic bombs are used as detonators for hydrogen fusion bombs.

Because hydrogen is lighter than uranium, more hydrogen atoms fit into a sample of the same weight. Thus, even though one fusion reaction releases less energy than one fission reaction, more hydrogen than uranium atoms can be packed into a nuclear weapon and many more fusion reactions can take place in the weapon than fission reactions can take place in a fission bomb. Fusion weapons, therefore, produce bigger explosions than fission weapons of the same physical bulk.

By 1954, a new feature had been added to the hydrogen bomb to create an even more dangerous weapon. Like earlier hydrogen bombs, this weapon was detonated with the explosion of an atomic or fission weapon. This raised temperatures enough to cause the hydrogen atoms in the bomb to fuse and explode like a regular hydrogen bomb. The designers also enclosed this new bomb in a shell of uranium-238. Neutrons released from the fusion of hydrogen caused the uranium-238 in the surrounding jacket to undergo fission, adding to the power of the blast. This new device was, in effect, a fission-fusion-fission bomb.

The power or "yield" of a nuclear weapon is expressed in terms of how much TNT would be required to equal the weapon's blast. Units of kilotons (thousands of tons) and megatons (millions of tons) of TNT are used to describe nuclear blasts.

Effects of nuclear weapons. Nuclear weapons produce two important effects that are also produced by conventional, chemical explosives: they release heat and generate shock waves, or pressure fronts of compressed air that smash objects in their paths. The heat released in a nuclear explosion creates a sphere of burning, glowing gas that can range from hundreds of feet to miles in diameter, depending on the power of the bomb. This fireball emits a flash of heat that travels outward from the site of the explosion (ground zero), the area directly under the explosion. This heat can cause second degree burns to bare human flesh miles away from the blast site if the bomb is large enough. (Although this heat can start fires, it seems that much of the fire damage in Hiroshima and Nagasaki following the nuclear explosions resulted from damaged electrical, fuel, gas, and other systems following physical damage caused by the shock or blast wave that accompanied the explosion.)

The shock wave produced when a nuclear weapon explodes creates a front of moving air more powerful than any produced by a natural storm. Destructive winds follow the front of displaced air, causing more damage to objects in their path. Many nuclear weapons are designed to be detonated high above their targets to take advantage of this shock effect. The more powerful the bomb, the higher in the sky it will be detonated. The fission bombs dropped on Japan (Hiroshima, 13.5 kilotons; Nagasaki, 22 kilotons) exploded between 1,500 and 2,000 feet (458–610 m) above their targets. A bomb with the power of 10 megatons is capable of destroying most houses within a distance of more than 10 miles from the blast site.

Unlike conventional explosives, nuclear devices can also release significant amounts of radioactivity and pulses of electromagnetic energy. Radioactivity is the release of fast particles and high-energy photons from unstable atomic nuclei. Besides the greater explosive power of nuclear weapons, radiation is the primary feature that most clearly distinguishes chemical from nuclear explosions. Radiation can kill outright at high doses and cause illnesses, including cancer, at lower doses. The initial burst of radiation during a nuclear explosion is made up of X rays, gamma rays, and neutrons. The energy of this radiation is so high that it can often penetrate buildings. Radioactive materials then contaminate the explosion site and often enter the atmosphere where they can travel thousands of miles before falling back to earth. This source of radiation is called radioactive fallout. Radioactive fallout can harm living things for years following a nuclear explosion. Fission bombs and fission-fusion-fission bombs produce more fallout than hydrogen bombs because the fusion of hydrogen atoms generates less radioactive byproducts than does fission of uranium or plutonium.

Electromagnetic pulses (EMPs) are also produced by nuclear weapons that are exploded at high altitudes, and are caused by the interaction of radiation from the explosion with electrons in the atmosphere and with the Earth's magnetic field. EMPs are essentially powerful radio waves that can destroy many electronic circuits.

The effects of fires and destruction following a largescale nuclear war could even change the climate of the planet. In 1983 a group of scientists, including U.S. astronomer Carl Sagan (1934–1996), published the "nuclear winter" theory, which suggested that particles of smoke and dust produced by fires caused by many nuclear explosions would, for a time, block the Sun's rays from reaching the surface of Earth. This, in turn, would reduce temperatures and change wind patterns and ocean currents. These climatic changes, according to the theory, could destroy crops and lead to the death by famine of many more animals and humans than were killed outright by nuclear explosions. Some scientists have challenged these predictions, but others, including some United States government agencies, support them. On the other hand, there is no controversy about whether a large-scale nuclear war could kill hundreds of millions of people and imperil the future of modern civilization, even apart from nuclear winter effects.

Modern nuclear weapons. Today nuclear weapons are built in many sizes and shapes not available in the 1940s and 1950s, and are designed for use against many different types of military and civilian targets. Some weapons are less powerful than 1,000 tons of TNT, while others have the explosive force of millions of tons of TNT. Small nuclear shells can be fired from cannons. Nuclear warheads mounted on missiles can be launched from land-based silos, ships, submarines, trains, and large wheeled vehicles. Several warheads can be fitted into one missile and directed to different targets in the same geographic area upon reentry into the Earth's atmosphere. These multiple independently-targeted reentry vehicles (MIRVs) can release 10 or so individual nuclear warheads far above their targets, making enemy interception more difficult and increasing the deadliness of each individual missile.

In general, nuclear weapons with "low" yields (in the kiloton, rather than the megaton, range) are termed "tactical," and are designed to be used in battle situations against specific military targets, such as a concentration of enemy troops or tanks, a naval vessel, or the like. These weapons are termed tactical because the word tactics, in military jargon, refers to the relatively small-scale maneuvers undertaken to win particular battles. Larger nuclear weapons are classed as "strategic," because the word strategy, again in military jargon, refers to the large-scale maneuvers undertaken to win whole wars. Strategic nuclear weapons are targeted mostly at cities and at other nuclear weapons, and are generally designed to be dropped by bombers or launched on ballistic missiles; tactical nuclear weapons are delivered by smaller devices over shorter distances. However, one nation's "tactical" warhead may be another's "strategic" warhead: Russia, for example, maintains that U.S. tactical warheads in Western Europe are in fact strategic warheads, because they can strike targets inside Russia itself, while Russian "tactical" warheads in the same arena cannot strike the U.S. heartland.

In the summer of 2002, the George W. Bush administration sought and received permission from Congress to design a new class of nuclear weapons: "mini-nukes" are relatively low-yield tactical nuclear weapons for use against underground bunkers and other small battlefield targets. Also in 2002, the U.S. military—according to a secret Pentagon document leaked to the press—drew up an official set of contingency plans for attacking seven countries with nuclear weapons (China, Russia, Iraq, North Korea, Iran, Libya and Syria). Advocates of these new weapons point to the uniquely powerful, compact "punch" that can be delivered by a nuclear weapon; critics argue that even a small nuclear weapon may cause many civilian casualties, and, more important, that actual use of a nuclear weapon of any size would break the taboo on such use that has held since the end of World War II, making the use of larger, more destructive nuclear weapons more likely in future conflicts. Some analysts stressed that the Pentagon's explicit willingness to use nuclear weapons in a "first-use" fashion, that is, in response to "unexpected military situations" not involving attack on U.S. forces by nuclear weapons, or to use them on targets (e.g., deep bunkers) resistant to conventional explosives signaled a major shift in United States nuclear use doctrine.

Even the ability of nuclear weapons to release radioactivity has been exploited to create different types of weapons. "Clean bombs" are weapons designed to produce as little radioactive fallout as possible. A hydrogen bomb without a uranium jacket would produce relatively little radioactive contamination, for example. A "dirty bomb" could just as easily be built, using materials that contribute to radioactive fallout. Such weapons could also be detonated near Earth's surface to increase the amount of material that could contribute to radioactive fallout. "Neutron" bombs have been designed to shower battle fields with deadly neutrons that can penetrate buildings and armored vehicles without destroying them. Any people exposed to the neutrons, however, would die. (Neutron bombs also destroy with blast effects, but their deadly radiation zones extend far beyond the site of their explosions).

The United States and Russia signed a Strategic Arms Reduction Treaty in 1993 to eliminate two thirds of their nuclear warheads in 10 years. By 1995, nearly 2,500 nuclear warheads had been removed from bombers and missiles in the two countries, according to U.S. government officials. ("Elimination," in this context, does not necessarily mean dismantlement; many of the weapons that have been "eliminated" by the treaty have been put in storage.) Although thousands of nuclear weapons still remain in the hands of many different governments, especially those of the U.S. and the Russian Federation, recent diplomatic trends have at least helped to lower the number of nuclear weapons in the world. This has caused many people to assume that the danger of nuclear weapons evaporated with the end of the Cold War.

However, the number of nations possessing nuclear weapons continues to increase, and the possibility of nuclear weapons being used against human beings for the first time since World War II may be larger than ever. In May 1995, more than 170 members of the United Nations agreed to permanently extend the Nuclear Non-Proliferation Treaty, first signed in 1960. Under the terms of the treaty, the five major countries with nuclear weapons—the United States, Britain, France, Russia, and China—agreed to commit themselves to eliminating their arsenals as an "ultimate" goal. The other 165 signatory nations agree not to acquire nuclear weapons. Israel, which is believed to possess nuclear weapons (but officially denies doing so), did not sign the treaty. Two other nuclear powers also refused to renounce nuclear weapons: India and Pakistan, each of which probably possess several dozen nuclear weapons, have fought a number of border wars in recent decades, and in 2002 came close, as many observers thought, to fighting a nuclear war. As of 2003, North Korea had reactivated its nuclear-weapons-material production facilities and was engaged in a tense diplomatic standoff with the United States, which insisted that North Korea abandon its nuclear-weapons program.

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Nuclear Weapons

Nuclear Weapons. The possibility of creating nuclear weapons of almost unimaginable destructive power was first realized in the 1930s as physicists developed a fundamental understanding of the nucleus of the atom. A nuclear explosion is created when heavy nuclei are split—or fissioned—into several of their component parts that are smaller and more stable.

Impact of Nuclear Weapons.

Nuclear fission is a fundamentally different process from chemical explosions that occur in conventional high‐explosive or incendiary bombs. In chemical explosions, larger molecular structures are broken apart and rearranged into smaller parts, but the individual atomic nuclei remain untouched. A chemical explosion produces a sudden release of energy that generates an explosive blast, whose resulting high air pressures and strong winds can crush and knock down nearby structures and people. In the case of early nuclear weapons based on the fission process, the energy release, which occurs in microseconds, is enormously larger because the nuclear bonds that hold nuclei together and are broken during fission are so much stronger than the chemical bonds that bind atoms into molecules. Since the nuclear forces are typically 100,000 to 1 million times stronger than the electrical ones responsible for molecular structures, the resultant energy releases are correspondingly larger.

The nuclear blast is so powerful that it can crush objects many miles away with high winds in excess of 150 mph generated at distances greater than a mile. The release of the enormous energy in a nuclear explosion leads to extremely high temperatures, comparable to those that occur at the center of the Sun, causing massive and deadly fires. As a measure of comparison, the temperatures generated by nuclear weapons are hundreds to thousands of times higher than the temperatures on the surface of the Sun, which heats the surface of the Earth from a distance of more than 90 million miles. Dangerous radioactive fallout is also spread over large distances by the resulting nuclear radiation emerging with the nuclear debris.

The ability to release such enormous energy from single weapons, on a scale unparalleled in human history, profoundly alters the very nature of war, as well as its consequences. An appreciation of the consequences of a nuclear explosion can be learned from the experience of the only nuclear weapons used in war, the atomic bombs dropped by U.S. air forces on Hiroshima and Nagasaki in 1945. These two weapons devastated two entire cities. They had yields of 15–20 kilotons. That measure simply means that the energy release was the same as that from detonating 15,000–20,000 tons of TNT (TNT is an acronym for the chemical formula of dynamite). By way of comparison, the largest conventional bombs used in World War II—the so‐called blockbusters used by the Royal Air Force (RAF)—detonated 10 tons (20,000 pounds) of TNT.

Those fission bombs of 1945 are no more than primitive versions of the first stage, or triggers, of modern nuclear weapons, whose yields range into the megatons, or millions of tons of TNT equivalent, and whose deadly devastating impact ranges over many miles. (One kiloton is equivalent to 2 million pounds of TNT; 1 megaton is equivalent to 2 billion pounds of TNT.) In modern nuclear weapons, such fission triggers are known as the primaries. They ignite a secondary stage by creating very high temperatures in order to generate still larger quantities of energy by driving together, or fusing, light nuclei into more stable ones. This is known as fusion. Such modern weapons are commonly referred to as thermonuclear weapons—or, more simply, H‐bombs.

The effect of a 1‐megaton thermonuclear weapon has an energy release 100,000 times greater than the largest 10‐ton blockbusters of World War II; the area destroyed by blast would be several thousand times larger than that leveled by such blockbusters. Collateral destruction and casualties due to fires and radioactive fallout would extend even further than the area destroyed by blast.

Soon after World War II, it was realized that the existence of nuclear weapons posed a new and fearsome threat to modern civilization and that it was vital to treat them differently from “conventional”—nonnuclear—weapons. Serious initiatives during the decade immediately following WWII tried to bring these terrifying new weapons under international control. These efforts failed as the confrontation between the Western powers and the Soviet Union and its allies grew into a cold war. Fueled by this dangerous competition during the 1960s, the individual nuclear arsenals of the United States and the Soviet Union accumulated to tens of thousands of warheads. In addition, France, England, and China acquired their own, albeit much smaller, nuclear arsenals. Furthermore, the newly developed delivery systems of intercontinental‐range, and in particular, land‐based intercontinental ballistic missiles (ICBMs)—and long‐range ballistic missiles on submarines (SLBMs) moving about invisibly under the surface of the oceans—brought the threat of nuclear annihilation very close to home, less than thirty minutes away from a nation's borders.

Difficulty of Protection Against Nuclear Weapons.

It also became clear before long that there was no known or prospective technology that could provide a defense against a determined nuclear attack. In contrast to previous wars, essentially nothing would be left of a large urban “target”—its population and industry—if just one, or at most a few, nuclear warheads exploded over it. Witness the bombings of Hiroshima and Nagasaki.

A defense would have to be essentially perfect to provide protection against nuclear weapons, and that is neither a realistic standard of performance today nor a prospective one for future military systems. In World War II, during the Battle of Britain, the RAF defense system managed to destroy no more than one in ten of the attacking planes. At such a rate, the German Air Force was reduced faster than it could replace its losses. At the same time, cities like London could put out the fires and rebuild after the damage. Human defenselessness is a basic fact of the nuclear age. It is also troubling since it denies one of the most basic instincts of the human race: to defend ourselves, our families, our friends, our vital interests. Recognition of the ineffectiveness of defenses against the almost unimaginable destructive potential of a massive attack by nuclear bombs led the United States and the former Soviet Union to acknowledge that their very survival was based on mutual deterrence—ensuring that nuclear weapons were not used.

Basic Physical Processes in Nuclear Weapons.

The first step in detonating a thermonuclear weapon is to ignite the high explosive that causes a shock wave to travel inward and compress the nuclear material the explosive surrounds, known as the pit. At the same time, a strong source of neutrons is activated to flood the compressed pit.

If the material in the compressed pit reaches a condition known as criticality, the neutrons initiate a strong fission chain reaction. This is the fission, or primary, stage of a thermonuclear explosion. In a chain reaction, an incoming neutron splits the nucleus of fissile material (either an isotope of uranium, U235, that occurs in nature, or of plutonium, Pu239, that is man‐made), releasing at least two neutrons, which then run into other fissile material, producing more neutrons, which then run into other fissile material, and so on. Thus, in successive steps, or “generations,” of fission, the neutrons will multiply: 2, 2 × 2, 2 × 2 × 2, … After very roughly 100 generations, if the fissile material can be held together long enough, (i.e., for microseconds), enough nuclei will have fissioned and enough energy will have been created to generate an explosive equivalent to 10 kilotons or so of TNT.

Several years after the development of such first‐generation fission bombs, weapons designers concentrated on improving their performance by using the material more efficiently. U.S. and Soviet weapons technology advanced rapidly after the first Soviet nuclear detonation, “Joe 1,” in 1949. The biggest advance occurred when the process of fusion was introduced into the explosive process. Fusion, in contrast to fission, involves combining, or fusing together, several nuclei of the lightest elements, such as hydrogen isotopes, to form more stable heavy ones. High temperatures are required to ignite the fusion process effectively. This is because at high temperatures, individual nuclei acquire high speeds, and move sufficiently rapidly to push their way though their mutual electric repulsion and get near enough to each other to collide and “fuse” together. The new nucleus thus formed is generally more stable, leading to the release of a large energy, plus more neutrons. Fusion is the process fueling the Sun's burning.

Modern weapons with both fission and fusion stages are called thermonuclear or hydrogen bombs. In a thermonuclear weapon, the primary, or fission, stage creates the necessary high temperatures to ignite the fusion stage, which provides additional neutrons to initiate still more fission, thereby releasing much more energy. A thermonuclear weapon can be built with virtually no limit on the amount of fusion materials it contains. Such weapons generate explosions as large as tens of megatons of TNT, or the equivalent of billions of pounds of TNT. In thinking about the totality of destruction in a nuclear war waged with modern thermonuclear weapons of such enormous yield, it is well to keep in mind that many of the destructive effects of nuclear weapons were not anticipated, and were discovered with surprise by atomic scientists when they were used or tested. This calls for great humility when it comes to predicting the consequences of nuclear warfare.

Since 1945, the total number of known nuclear tests, worldwide, adds up to some 2,000. A major purpose of testing has been to validate and confirm appropriate performance specifications for new weapons types designed in response to military needs formulated during the Cold War. Starting in the mid‐1950s, U.S. weapons were designed and built “ready to go.” They conserved special nuclear materials (SNM)—the fissile materials Pu239 and U235—and were essentially maintenance‐free, ready to go at any time. “Ready” means that no physical changes or steps such as inserting the SNM had to be made in order to detonate a bomb. One merely had to launch and detonate the warhead by signal.

In response to growing worldwide concerns about radioactive fallout from continued nuclear testing, the United States, the Soviet Union, and the United Kingdom joined in 1963 in a Limited Test Ban Treaty that forbade testing aboveground, in the atmosphere, underwater, and in outer space. Only underground testing was allowed. A further restriction on testing was negotiated in 1974, limiting the yields of underground tests to a maximum of 150 kilotons, roughly ten times the yield of the Hiroshima bomb. This so‐called Threshold Test Ban Treaty was generally obeyed henceforth, though it was not ratified until 1990.

In 1992, progress in negotiated reductions in the nuclear arsenals, and further progress in reducing reliance on nuclear weapons after the end of the Cold War, led President George Bush to rule out nuclear weapons tests for new warheads and to declare a nine‐month moratorium on all nuclear testing. This moratorium was continued by his successor and has also been honored by Russia and the United Kingdom. On 11 August 1995, President Bill Clinton announced U.S. support for negotiating a comprehensive test ban treaty in 1996. The treaty would be of unending duration, and would include, as do all such tests, a “supreme national interest” clause should unanticipated circumstances present compelling arguments for renewed tests. Such arguments might arise if there were serious reversals from the present progress toward reducing nuclear danger in the world, or if unforeseen technical problems arose over time in the enduring nuclear stockpile.

By the best current technical judgment, U.S. weapons appear to be safe, reliable, age‐stable, and fully adequate for deterrence; but it will be a new challenge to maintain that confidence without being able to conduct tests that produce any nuclear yield. Under its recently formulated program for stockpile stewardship and management, the United States has accepted this challenge, following a comprehensive scientific review of prospects and needs for its nuclear arsenal. So have the United Kingdom, Russia, France, and China.

On September 1996 President Clinton was the first world leader to sign the Comprehensive Test Ban Treaty at the United Nations in New York. Soon thereafter the other declared nuclear powers—England, France, China, and Russia—also signed, and as of November 1998 150 nations have signed the Treaty and twenty‐one have ratified it. For it to go into effect it must be ratified by all forty‐four nuclear capable nations, i.e., nations with nuclear reactors for research or for civilian energy production, in addition to those with nuclear weapons. A Comprehensive Test Ban after more than 2,000 tests over a 50‐year period would be a tremendous achievement. Efforts to accomplish that goal are currently in progress, together with continuing efforts to reduce the size of the nuclear arsenals at the Strategic Arms Reduction Talks (START) underway between the U.S. and Russia.[See also Arms Control and Disarmament: Nuclear; Cold War: External Course; Cold War: Domestic Course; War Plans; Weaponry; World War II: Military and Diplomatic Course.]

Bibliography

Margaret Gowing , Britain and Atomic Energy, 1939–1945, 1964. Samuel Glasstone and Philip J. Dolan, eds., The Effects of Nuclear Weapons, 3rd ed. 1977. Richard Rhodes , The Making of the Atomic Bomb, 1986. Robert Serber , The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb, 1992. David Holloway , Stalin and the Bomb, 1994. Richard Rhodes , Dark Sun: The Making of the Hydrogen Bomb, 1995.

Sidney Drell

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Nuclear Weapons

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COPYRIGHT 2002 The Gale Group, Inc.

Nuclear weapons

Nuclear weapons are destructive devices that derive their power from nuclear reactions. The term weapon refers to devices such as bombs and warheads designed to deliver explosive power against an enemy. The two types of nuclear reactions used in nuclear weapons are nuclear fission and nuclear fusion. In nuclear fission, large nuclei are broken apart by neutrons, forming smaller nuclei, accompanied by the release of large amounts of energy. In nuclear fusion, small nuclei are combined with each other, again with the release of large amounts of energy.

Fission weapons

The design of a fission weapon is quite simple: all that is needed is an isotope that will undergo nuclear fission. Only three such isotopes exist: uranium-233, uranium-235, and plutonium-239. Fission occurs when the nuclei of any one of these isotopes is struck by a neutron. For example:

neutron + uranium-235 → fission products + energy + more neutrons

The production of neutrons in this reaction means that fission can continue in other uranium-235 nuclei. A reaction of this kind is known as a chain reaction. All that is needed to keep a chain reaction going in uranium-235 is a block of the isotope of sufficient size. That size is called the critical size for uranium-235.

One of the technical problems in making a fission bomb is producing a block of uranium-235 (or other fissionable material) of exactly the right size—the critical size. If the block is much less than the critical size, neutrons produced during fission escape to the surrounding air. Too few remain to keep a chain reaction going. If the block is larger than critical size, too many neutrons are retained. The chain reaction continues very rapidly and the block of uranium explodes before it can be dropped on an enemy.

The simplest possible design for a fission weapon, then, is to place two pieces of uranium-235 at opposite ends of a weapon casing. Springs are attached to each piece. When the weapon is delivered to the enemy (for example, by dropping a bomb from an airplane), a timing mechanism is triggered. At a given moment, the springs are released, pushing the two chunks of uranium-235 into each other. A piece of critical size is created, fission begins, and in less than a second the weapon explodes.

Words to Know

Fission bomb: An explosive weapon that uses uranium-235 or plutonium-239 as fuel. Also called an atom bomb.

Fusion bomb: An explosive weapon that uses hydrogen isotopes as fuel and an atom bomb as a detonator.

Isotopes: Two or more forms of an element that have the same chemical properties but that differ in mass because of differences in the number of neutrons in their nuclei.

Nuclear fission: A nuclear reaction in which an atomic nucleus splits into two or more fragments with the release of energy.

Nuclear fusion: A nuclear reaction in which two small atomic nuclei combine with each other to form a larger nucleus with the release of energy.

Radioactivity: The property possessed by some elements of spontaneously emitting energy in the form of particles or waves by disintegration of their atomic nuclei.

The only additional detail required is a source of neutrons. Even that factor is not strictly required since neutrons are normally present in the air. However, to be certain that enough neutrons are present to start the fission reaction, a neutron source is also included within the nuclear weapon casing.

Fusion weapons

A fusion weapon obtains the energy it releases from fusion reactions. Those reactions generally involve the combination of four hydrogen atoms to produce one helium atom. Such reactions occur only at very high temperatures, a few million degrees Celsius. The only way to produce temperatures of this magnitude on Earth is with a fission bomb. Thus, a fusion weapon is possible only if a fission bomb is used at its core.

Here is how the fusion bomb is designed: A fission bomb (like the one described in the preceding section) is placed at the middle of the fusion weapon casing. The fission bomb is then surrounded with hydrogen, often in the form of water, since water is two parts hydrogen (H2O). Even more hydrogen can be packed into the casing, however, if liquid hydrogen is used.

When the weapon is fired, the fission bomb is ignited first. It explodes, releasing huge amounts of energy and briefly raising the temperature inside the casing to a few million degrees Celsius. At this temperature, the hydrogen surrounding the fission bomb begins to fuse, releasing even larger amounts of energy.

The primary advantage that fusion weapons have over fission weapons is their size. Recall that the size of a fission explosion is limited by the critical size of the uranium-235 used in it. A weapon could conceivably consist of two pieces, each less than critical size; or three pieces, each less than critical size; or four pieces, each less than critical size, and so on. But the more pieces used in the weapon, the more difficult the design becomes. One must be certain that the pieces do not come into contact with each other and suddenly exceed critical size.

No such problem exists with a fusion bomb. Once the fission bomb is in place, the casing around it can be filled with ten pounds of hydrogen, 100 pounds of hydrogen, or 100 tons of hydrogen. The only limitation is how large—and heavy—the designer wants the weapon to be.

The power difference between fission and fusion bombs is illustrated by the size of early models of each. The first fission bombs dropped on Japan at the end of World War II were rated as 20 kiloton bombs. The unit kiloton is used to rate the power of a nuclear weapon. It refers to the amount of explosive power produced by a thousand tons of the chemical explosive TNT. In other words, a 20-kiloton bomb has the explosive power of 20,000 tons of TNT. By comparison, the first fusion bomb ever tested had an explosive power of 5 megatons, or 5 million tons of TNT.

Effects of nuclear weapons

In some respects, the effects produced by nuclear weapons are similar to those produced by conventional chemical explosives. They release heat and generate shock waves. Shock waves are pressure fronts of compressed

air created as hot air expands away from the center of an explosion. They tend to crush objects in their paths. The heat released in a nuclear explosion creates a sphere of burning gas that can range from hundreds of feet to miles in diameter, depending on the power of the bomb. This fireball emits a flash of heat that travels outward from the site of the explosion or ground zero, the area directly under the explosion. The heat from a nuclear blast can set fires and cause serious burns to the flesh of humans and other animals.

Nuclear weapons also produce damage that is not experienced with chemical explosives. Much of the energy released during a weapons blast occurs in the form of X rays, gamma rays, and other forms of radiation that can cause serious harm to plant and animal life. In addition, the isotopes formed during fission and fusion—called fission products—are all radioactive. These fission products are carried many miles away from ground zero and deposited on the ground, on buildings, on plant life, and on animals. As they decay over the weeks, months, and years following a nuclear explosion, the fission products continue to release radiation, causing damage to surrounding organisms.

Nuclear weapons today

Today nuclear weapons are built in many sizes and shapes. They are designed for use against various different types of military and civilian targets. Some weapons are rated at less than 1 kiloton in power, while others have the explosive force of millions of tons of TNT. Small nuclear shells can be fired from cannons. Nuclear warheads mounted on missiles can be launched from land-based silos, ships, submarine, trains, and large-wheeled vehicles. Several warheads can even be fitted into one missile. These MIRVs (or multiple independent reentry vehicles), can release up to a dozen individual nuclear warheads along with decoys far above their targets, making it difficult for the enemy to intercept them.

Even the ability of nuclear weapons to release radioactivity has been exploited to create different types of weapons. Clean bombs are weapons designed to produce as little radioactive fallout as possible. A hydrogen bomb without a uranium jacket would produce relatively little radioactive contamination, for example. A dirty bomb could just as easily be built with materials that contribute to radioactive fallout. Such weapons could also be detonated near Earth's surface to increase the amount of material that could contribute to radioactive fallout. Neutron bombs have been designed to shower battlefields with deadly neutrons that can penetrate buildings and armored vehicles without destroying them. Any people exposed to the neutrons, however, would die.

Radioactive Fallout

"The gift that keeps on giving."

That phrase is one way of describing radioactive fallout. Radioactive fallout is material produced by the explosion of a nuclear weapon or by a nuclear reactor accident. This material is blown into the atmosphere and then falls back to Earth over an extended period of time.

Radioactive fallout was an especially serious problem for about 20 years after the first atomic bombs were dropped in 1945. The United States and the former Soviet Union tested hundreds of nuclear weapons in the atmosphere. Each time one of these weapons was tested, huge amounts of radioactive materials were released to the atmosphere. They were then carried around the globe by the atmosphere's prevailing winds. Over long periods of time, they were carried back to Earth's surface or settled to the ground on their own (because of their weight).

More than 60 different kinds of radioactive materials are formed during the explosion of a typical nuclear weapon. Some of these decay and become harmless in a matter of minutes, hours, or days. Other remain radioactive for many years.

An example of a long-lived radioactive material is strontium-90. Strontium-90 loses one-half of its radioactivity every 28 years. It can continue to pose a threat, therefore, for more than a century. The special problem presented by strontium-90 is that it behaves very much like another element—calcium. When it falls to Earth, it is taken up by grass, leaves, and other plant parts. When cows eat grass, they take in strontium-90. The strontium-90 is incorporated into their milk, which is then taken in by humans. Once in the human body, strontium-90 is incorporated into bones and teeth in much the same way that calcium is. Children growing up in the 1960s may still have low levels of strontium-90 in their systems—a "long-lasting gift" from the makers of nuclear weapons.

Nuclear weapons treaties

The United States and Russia signed a Strategic Arms Reduction Treaty (START I) in 1991, which called for the elimination of 9,000 nuclear warheads. Two years later, the two countries signed the START II Treaty, which called for the reduction of an additional 5,000 warheads beyond the number being reduced under START I. Under START II, each country agreed to reduce its total number of strategic nuclear warheads from bombers and missiles by two-thirds by 2003. In 1997, the United States and Russia agreed to delay the elimination deadline until 2007. By that time, each side must have reduced its number of nuclear warheads from 3,000 to 3,500.

Although thousands of nuclear weapons still remain in the hands of many different governments, recent diplomatic trends have helped to lower the number of nuclear weapons in the world. In May 1995, more than 170 members of the United Nations agreed to permanently extend the Nuclear Non-Proliferation Treaty (NPT), which was first signed in 1968. Under terms of the treaty, the five major countries with nuclear weapons—the United States, Britain, France, Russia, and China—agreed to commit themselves to eliminating their arsenals as an ultimate goal and to refusing to give nuclear weapons or technology to any non-nuclear-weapon nation. The other 165 member nations agreed not to acquire nuclear weapons. Israel, which is believed to possess nuclear weapons, did not sign the treaty. Two other nuclear powers, India and Pakistan, refused to renounce nuclear weapons until they can be convinced their nations are safe without them. As of early 2000, a total number of 187 nations had agreed to the NPT. Cuba, India, Israel, and Pakistan were the only nations that had not yet agreed to the treaty.

[See alsoNuclear fission; Nuclear fusion ]

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Warfare, Nuclear

Nuclear warfare consists of armed conflict between states in which one or more sides employ nuclear weapons. Because no war since World War II has involved nuclear weapons, how such a conflict would be triggered and executed is largely a matter of theoretical speculation. Furthermore, the sophistication and destructive scale of the nuclear weapons used against Japan pale in comparison to modern weapons. A nuclear war between two nuclear states would result in the deaths of hundreds of thousands, if not millions, of people. The areas surrounding locations hit with nuclear weapons would be highly contaminated with radioactive fallout. In addition, depending on the number of weapons used, such a war could have long-term devastating effects on the earth’s ecosystems and atmosphere. Because today only a few countries possess nuclear weapons, the number of conflicts that could conceivably escalate to nuclear war is limited. These countries include the United States, Russia, China, Great Britain, France, Israel, Pakistan, India, and most likely North Korea. Proliferation to additional countries remains a continual problem for international security.

The destructive power of nuclear weapons makes nuclear warfare fundamentally different from traditional conventional warfare. The single fifteen-kiloton bomb dropped on Hiroshima, for example, destroyed 80 percent of the city, immediately killing between 66,000 and 80,000 people and injuring roughly 70,000. As Wilfred Burchett (1945), the first journalist to report on the devastation, put it: “Hiroshima does not look like a bombed city. It looks as if a monster steamroller has passed over it and squashed it out of existence.” The city of Hiroshima estimates that the total killed from the explosion and subsequent radiation poisoning is over 240,000. Nagasaki saw high casualties as well, with 39,000 immediately killed and 25,000 injured, and many others who later died due to radiation poisoning.

How nuclear weapons would be used in war, and whether a nuclear war between two nuclear powers could even be won, has been a central problem facing military strategists and planners. Because of the devastating effects of nuclear weapons, they are less useful in battle than conventional weapons. However, because such weapons exist and because no country can be sure of what another’s intentions would be in the event that they were to gain a dominant nuclear advantage, the major nuclear powers have continued to develop nuclear war strategies. That said, nuclear powers have shown extreme caution when conflict develops with other nuclear powers, out of fear that a minor crisis could escalate into an unwanted nuclear war; this was displayed during the 1962 Cuban missile crisis. Nuclear powers have also been reluctant to use their nuclear capabilities in conflicts against a nonnuclear power, as with the United States in Vietnam or Israel in its 1973 war with Egypt and Syria.

Nuclear strategy makes distinctions between counterforce and countervalue. Counterforce strategies are intended to affect an opponent’s capabilities, whereas countervalue capabilities affect an opponent’s will. Counterforce targets an opponent’s armed forces and military-industrial installations, limiting the opponent’s ability to retaliate in a counterattack. A country that struck first in a nuclear war would most likely employ a counterforce targeting strategy. Countervalue strategies target an opponent’s cities—that is, things of human and emotional value. A country that feared a nuclear attack by an opponent would threaten a countervalue retaliation with the hope that even the possibility of its opponent losing one city would be enough to deter a nuclear first strike. Of course, for a countervalue deterrent to be effective, the country being deterred must believe that at least some of its opponent’s nuclear arsenal would survive a first strike. It also must believe that the damage that that remaining arsenal could deliver would outweigh the benefits gained from striking first. With nuclear weapons it is oftentimes difficult to distinguish between what constitutes a counterforce and what constitutes a countervalue target. Military targets are often found in population centers and given the large radius of damage caused by a nuclear attack it is extremely difficult to target the one without hitting the other. For example, when U.S. war planners began looking for military-industrial targets across the Soviet Union after 1945, every sizeable Soviet city was deemed to contain military targets.

The logic behind counterforce and countervalue, as well as first-strike versus second-strike capabilities, is encompassed in the idea of mutual assured destruction (MAD). MAD describes a state of affairs in which both sides’ nuclear forces are such that a sufficient percent would remain after an attack that it would still be possible to bring about the near total destruction of the attacking state. The hope of MAD was that this mutual suicide pact would prevent either side from ever being tempted to use nuclear weapons. In order for MAD to be viable, however, it required the United States and the Soviet Union to stockpile large quantities of nuclear weapons and to develop targeting lists of single targets that would be hit multiple times. In addition, U.S. and Soviet force structures were designed to survive a possible first strike. Achieving this involved spending on difficult-to-target nuclear forces, such as submarines, hardened missile silos, and continually in-flight bomber fleets.

Those who wanted to maintain a strategic nuclear balance put emphasis on developing less-accurate, single large warheads that would be unable to hit anything smaller than area targets. Such missiles would be effective against countervalue targets, which do not require precise accuracy to be effective; but would be less effective hitting silos or airfields.

It was feared, however, that a number of innovations and weapons systems could disrupt this strategic balance. Such a disruption could lead one side to perceive a “window of opportunity” in which they would be tempted to launch a preventive war before new technological innovations either restored the balance or shifted first-strike advantage to the opponent. For example, declarations of “bomber gaps” or “missile gaps” by United States politicians, particularly in the late 1950s and early 1960s, led many to fear that (alleged) Soviet advantage could lead to a devastating first strike. The development of multiple independently targeted reentry vehicles (MIRVs), which are intercontinental ballistic missiles (ICBMs) carrying multiple warheads that can be individually programmed to hit separate targets, was also seen as destabilizing, as one missile could target multiple ICBM silos. This offensive advantage, it was feared, could tempt one country to launch a preemptive attack out of fear that it would suffer a debilitating blow if it were not the one to attack first.

Another potential innovation capable of disrupting strategic balance is some form of missile defense system. While an effective missile defense system could protect a country from nuclear annihilation, it would also provide it with an overwhelming first-strike advantage, as its opponent would be unable to retaliate, regardless of the number of surviving nuclear forces. There would also be an incentive to strike sooner rather than later, as military history has shown that all defenses are eventually penetrable.

Arms control agreements between the United States and the Soviet Union during the Cold War were primarily designed to stabilize the strategic balance between the two sides. By limiting each side’s ability to gain first-strike advantage, the hope was that neither side would be tempted to carry out a preemptive first strike. The Anti-Ballistic Missile (ABM) Treaty, Strategic Arms Limitation Talks (SALT I and II), the Strategic Arms Reduction Treaties (START I and II), and the Strategic Offensive Reduction Treaty (SORT) were all designed to provide a framework in which the United States and the Soviet Union (now Russia) could maintain a nuclear balance without engaging in a costly and potentially dangerous arms race.

Since the end of the Cold War, fears of a nuclear exchange between the United States and Russia have subsided. However, a number of concerns still remain. India and Pakistan, which both officially declared their nuclear status with a series of tests in 1997, have a long history of conflict, specifically over the contested Kashmir region. This history of conflict, their contingent border, and an underdeveloped command and control system, make a nuclear exchange (either intentional or accidental) a very real possibility.

It is also feared that a “rogue” state could develop a nuclear weapon and be able to hold the world hostage by threatening to use it against a major world city if its demands were not met. While the world could easily retaliate if such a threat were carried out, the question remains whether there would be a willingness to risk giving up an important city in the first place. It is this potentiality that has led world leaders to take aggressive stances (with mixed success) against such potential proliferators as North Korea, Iraq, Iran, and Libya.

The final fear is that a terrorist organization would be able to acquire a nuclear device by stealing, buying, or being given it from a country’s arsenal. This is a particularly difficult scenario because normal countervalue threats would not have a very strong deterrent effect on a small, decentralized, apocalyptic terrorist organization.

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Weaponry, Nuclear

Weaponry, Nuclear

The advent of the nuclear weapons age began on July 16, 1945, when the United States tested its first nuclear device in New Mexico at the Alamogordo Bombing Range, now known as the White Sands Missile Range. The successful nuclear explosion, named Trinity, was the end result of the Manhattan Project, a three-year, $1.9 billion ($26.9 billion in 2005 dollars) effort that brought hundreds of the world’s top scientists together to develop a weapon to be used in the United States’ war efforts against Japan and Germany. Nuclear weapons have been used in warfare on two occasions: on Hiroshima, Japan, on August 6, 1945, and on Nagasaki, Japan, on August 9, 1945. Both bombs were dropped by the United States. As of 2006, eight nations were known to possess nuclear weapons: the United States, Russia, the United Kingdom, France, China, Israel, India, and Pakistan. It is possible that North Korea also possesses a nuclear weapon. In 2003 North Korea claimed to have had successfully developed nuclear weapons. While North Korea has not tested a device, most intelligence estimates believe it is likely that it has nuclear capabilities. South Africa once possessed nuclear weapons but dismantled them in 1993 (see Cirincione, Wolfsthal, and Rajkumar 2005).

Nuclear weapons require fissionable materials. When a fissionable atom absorbs a neutron, it will split and release additional neutrons. In a nuclear chain reaction, those neutrons are absorbed into other fissionable atoms that subsequently split and release additional neutrons into other atoms. Nuclear explosions are the result of the rapid release of energy that comes from an uncontrolled nuclear chain reaction.

The two fissionable elements used in nuclear weapons are uranium and plutonium. Uranium is found in nature, but the specific fissionable isotope, uranium235, constitutes only 0.7 percent of all natural uranium. A nuclear weapon, however, requires uranium-235 to make up over 90 percent of the sample. In order to achieve such a high concentration, the uranium must go through an enrichment process that separates uranium-235 from the more common uranium-238 isotope. This has most commonly been achieved with centrifuges, but other methods, such as gaseous diffusion and electromagnetic isotope separation, have also been successful. Plutonium is not found in nature but is a product of the highly radioactive waste from a controlled chain reaction of uranium, usually performed in a nuclear reactor. To extract plutonium from this waste, a sophisticated chemical process is used. For a country seeking to establish a nuclear weapons program, these large-scale industrial and technical processes can be prohibitive.

Critical mass is the smallest amount of fissionable material that is needed to maintain a nuclear chain reaction. How much uranium or plutonium is needed to reach critical mass depends on various elements of weapon design, such as the shape of the fissile core (gun-type or sphere) or the effective use of reflectors to capture errant neutrons. Most estimates are that between 12 to 60 kilograms of weapons-grade uranium and 4 to 10 kilograms of plutonium are needed. In addition, the efficiency and yield of a weapon can be increased by adding a fusion fuel “booster,” such as lithium-6, as found in thermonuclear weapons.

The effects of a nuclear explosion are devastating. The majority of damage is caused by three main elements: blast effects, thermal heat, and ionizing radiation. For example, the bomb that was dropped on Hiroshima, a uranium-type device known as Little Boy, had a yield of 12.5 kilotons of TNT. Of the 76,000 buildings in Hiroshima, 48,000 were completely destroyed and another 22,000 were damaged. According to one study of the Hiroshima bombing, the temperature at the site of the explosion reached 5,400 degrees Fahrenheit and “primary atomic bomb thermal injury was found in those exposed within [2 miles] of the hypocenter” (quoted in Rhodes 1986, p. 714). The heat was so intense that people within a half mile of the fireball were reduced to bundles of smoking char. The number of deaths in Hiroshima due to the bomb is estimated to be 140,000, with an additional 60,000 dying from radiation effects over the next five years.

Since these early devices, the yield of nuclear weapons has grown considerably. Although never deployed, on October 30, 1961, the largest nuclear bomb ever tested was the Soviet Union’s “Tsar Bomba,” which had a maximum yield of 100 megatons. More commonly, modern nuclear weapons have yields ranging between one and 5.5 megatons.

For a one-megaton device, the damage would be even more widespread than at Hiroshima and Nagasaki. According to Ansley J. Coale (1985), the shockwaves from a one-megaton blast would destroy modern multistory buildings within 2.9 miles and unreinforced brick and wood buildings within 4.2 miles of impact. Damage to brick and wood buildings would be substantial up to 8.5 miles from the blast. Heat would cause third-degree burns to exposed skin and set fire to clothing within 4.2 miles. The gamma rays produced from such a blast would be almost immediately lethal to any exposed person within 2.5 miles. People exposed at a slightly greater distance (2.7 miles) would have about a 50 percent mortality rate within a month of the explosion. Finally, a nuclear explosion that makes contact with the ground (as opposed to an airblast) would create tremendous amounts of radioactive fallout that could spread over an area as far as 1,000 square miles downwind from the explosion. Estimates of what percentage would be killed in a one-megaton blast on an urban population vary from 11 percent to 25 percent of the total population, with an additional 16 to 25 percent injured. Of course, in a nuclear exchange between advanced nuclear weapons states, multiple bombs would likely be assigned to single targets, resulting in even higher levels of devastation.

The three main methods of delivery involve ballistic missiles, aircraft, and submarines. Delivery methods are tied to larger strategic and tactical issues related to nuclear deterrence. Nuclear states, such as the United States and the Soviet Union during the cold war, are concerned that a first-strike nuclear attack from another country could be so damaging that it would successfully eliminate any possibility for retaliation. As a result, states design their nuclear forces in such a way that a sufficient number of weapons would remain to respond with a devastating second strike. Many argue that the sole purpose of any nuclear weapon is to deter other states from ever using one. Some also fear that a terrorist organization could gain possession of a nuclear weapon and smuggle it into a major urban center.

Intercontinental ballistic missiles (ICBMs) are launched from reinforced below-ground silos and have ranges of more than 8,000 miles. Often, ICBMs are equipped with multiple warheads—multiple, independently targeted reentry vehicles (MIRV)—capable of hitting multiple targets. Shorter-range ballistic missiles, which could more easily be used in tactical or battlefield scenarios, have largely been eliminated from the arsenals of major nuclear states.

The appeal of aircraft and submarines is their mobility, as well as an enemy’s consequent difficulty in targeting them. Heavy-duty bombers, primarily equipped with up to twenty short-range attack missiles capable of hitting multiple targets, have the ability to penetrate enemy territory and withstand a great deal of abuse. Submarines carrying strategic nuclear missiles can remain below the surface for long periods and can launch missiles capable of hitting specific targets over distances of hundreds of miles. The possession of a nuclear-equipped submarine fleet gives a country a very credible second-strike deterrent.

Since the end of the cold war, both the United States and the former Soviet Union have worked to decrease their nuclear arsenals. However, many fear that tensions between other nuclear states, such as India and Pakistan, and the ongoing threat of further proliferation could result in the future use of nuclear weapons.

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NUCLEAR WEAPONS

The actions of countries in times of war are governed by international law that constantly changes with advancements in weapons technology. There is not, however, an international law that specifically addresses the use of nuclear weapons. The Geneva Conventions, in 1949, outlined rules to protect populations during armed conflict. They require distinguishing between civilians and soldiers, and prohibit indiscriminate methods of attack that are not directed at a specific military target. The conventions also prohibit weapons that cause unnecessary injury and those that cause long-term and severe environmental damage. Specific types of weapons are not mentioned. Many believe that given the extremely destructive power of nuclear weapons, they should be specifically prohibited. These critics contend that the use of nuclear weapons clearly violates international humanitarian law regarding armed conflict.

To clarify this issue, the United Nations General Assembly asked the international court of justice (ICJ) for an advisory opinion regarding the legality of the threat or use of nuclear weapons. The opinion of the ICJ, handed down on July 8, 1996, is the most authoritative statement regarding the legality of nuclear weapons under international law. The ICJ concluded unanimously that the threat or use of such weapons should be consistent with existing international laws. The ICJ did not declare such weapons specifically illegal, but did state that the threat or use of nuclear weapons would generally be contrary to the rules of international law applicable in armed conflict, leaving the issue of self-defense open.

Advocates of nuclear disarmament contend that based on this ruling of the ICJ, the threat or use of nuclear weapons violates U.S. as well as international law. Article VI of the United States Constitution states, "all treaties made, or which shall be made, under the authority of the United States, shall be the supreme law of the land." The reasoning is that since the threat or use of nuclear weapons violates international treaties that the United States has signed and ratified (e.g., the geneva convention), then the threat or use of these weapons should be illegal.

Since the ICJ opinion was delivered in 1996, direct actions by the public in support of nuclear disarmament have increased. Some courts have recognized the legality of such actions. In October 1999, a Scottish judge dismissed a case against three women who had caused damage at a base, which was part of a Trident nuclear submarine defense program. The judge cited the ICJ opinion and claimed that the women were justified in their actions because they were attempting to thwart the use of illegal weapons. In June 1999, a jury in the state of Washington found four activists not guilty of blocking traffic into a Trident nuclear submarine base. The court relied on international law, including the ICJ opinion.

The one international treaty that attempts to safeguard against the threat of nuclear weapons is the nuclear non-proliferation treaty (NPT). Under the treaty, the possession of nuclear weapons is prohibited by all states, except for the Nuclear Weapon States (NWS). The treaty defines an NWS as one that had manufactured and exploded a nuclear weapon or other nuclear explosive device prior to January 1, 1967, which limits membership to the United States, the former Soviet Union (and its successor state, Russia), the United Kingdom, France, and China. Those few states possessing nuclear weapons are under obligation, as set forth in Article VI of the NPT, to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament."

While the Nuclear Weapon States pledged to negotiate nuclear disarmament, the Non-Nuclear Weapon States (NNWS) pledged not to acquire nuclear weapons. As an incentive, the NNWS were promised assistance with research, production, and use of nuclear energy for peaceful purposes "without discrimination." Each NNWS also agreed to accept safeguards under the auspices of the international atomic energy agency. These safeguards do not apply to the NWS.

The NPT was signed in 1968, and entered into force in 1970. Its initial duration was 25 years. In 1995, it was extended indefinitely, with a review conference to be held every five years. Nearly every country in the world, 188 total, is a party to the NPT, with three notable exceptions: India, Israel, and Pakistan. Each of these countries possesses nuclear weapons. Under the ICJ opinion, however, the obligation to negotiate elimination of nuclear arsenals applies to those states as well as the NWS.

Nuclear waste storage has also become an issue. High level radioactive waste is generally material from the core of a nuclear reactor or nuclear weapon. This waste includes uranium, plutonium, and other highly radioactive elements made during fission. Most of these elements have extremely long half-lives (some longer than 100,000 years), which means it will be a long time before the waste will settle to safe levels of radioactivity.

In 1982, Congress enacted legislation in the hopes of solving the problem of nuclear waste disposal in the United States. The Nuclear Waste Policy Act (42 U.S.C.A. §§ 10101-10226) made the U.S. energy department responsible for finding a site and building and operating an underground disposal facility called a geologic repository. The recommendation to use a geologic repository dates back to 1957 when the National Academy of Sciences recommended that the best means of protecting the environment and public health and safety would be to dispose of the waste in rock deep underground.

Based on Energy Department findings, three sites were designated as possible repositories: Hanford, Washington; Deaf Smith County, Texas; and Yucca Mountain, Nevada. In 1987, Congress amended the Nuclear Waste Policy Act and directed the Energy Department to study only Yucca Mountain. Yucca Mountain is located in a remote desert approximately ninety miles northwest of Las Vegas, Nevada. On July 23, 2002, President george w. bush signed House Joint Resolution 87, allowing the Energy Department to take the next steps in establishing a repository. The state of Nevada and the city of Las Vegas filed a number of suits against the Energy Department and various other federal entities. These suits challenge such things as the lack of compliance with the Nuclear Waste Policy Act and faulty design of the proposed facility.

further readings

Burroughs, John. 1997. The Legality of Threat or Use of Nuclear Weapons: A Guide to the Historic Opinion of the International Court of Justice. Piscataway, N.J.: Transaction.

Evan, William M., and Ved P. Nanda, eds. 1995. Nuclear Proliferation and the Legality of Nuclear Weapons. Lanham, Md.: University Press of America.

Moxley, Charles J. 2000. Nuclear Weapons and International Law in the Post Cold War World. Lanham, Md.: Austin & Winfield.

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Nuclear Weapons

Dictionary of American History
COPYRIGHT 2003 The Gale Group Inc.

NUCLEAR WEAPONS

NUCLEAR WEAPONS derive their energy from the splitting (fission) or combination (fusion) of atomic nuclei. This category of weapons taken together may have finally fulfilled the wish of technologists throughout history for a weapon so terrible that it would make war between great powers obsolete. The twentieth century was the bloodiest in human history, yet no two nations possessing nuclear weapons fought a major war against one another.

The nuclear era began with the Manhattan Project, the secret American effort during World War II to construct an atomic bomb. On 6 July 1945 the world's first atomic explosion was created during a test in the New Mexico desert. On 6 and 9 August, respectively, the Japanese cities of Hiroshima and Nagasaki were devastated by atomic bombings, and on 10 August Japan offered to surrender. The wave of celebrations in the United States that followed the end of the war were tinged with an immediate sense of shock at the terrifying power of this new class of weaponry. In a world where the science fiction of

H. G. Wells had suddenly become a reality, anything seemed possible, and popular reactions to the bomb varied widely. Many feared that the next world war would result in the literal extinction of humankind, and to witnesses of two world wars in the space of three decades, a third world war seemed a virtual inevitability. Others searched for hope in the new "atomic world, " imagining the imminent creation of a world government, the abolition of war, or even a utopia where the atom eradicated disease and provided limitless electrical power. While no such utopia emerged, nuclear energy did eventually fight cancer and generate electricity. No aspect of American society escaped the cultural upheavals of the bomb. By the early 1950s even schoolchildren were instructed by a cartoon turtle that they "must be ready every day, all the time, to do the right thing if the atomic bomb explodes: duck and cover!"

Political, military, and intellectual elites within the United States also grappled with the implications of nuclear weapons. A group of academic nuclear theorists led by Bernard Brodie began developing theories of deterrence for a world where preventing war seemed to be more important than winning one. Military leaders hoped that the American monopoly on nuclear weapons would deter any potential aggressor for the time being, but even optimists did not expect this monopoly to last more than a decade. If war with the Soviet Union did come, and "war through miscalculation" as well as by conscious design was always a fear, planners did not believe that the use of tens or even hundreds of atomic bombs would necessarily bring victory. Expansion of the American nuclear stockpile continued at the maximum possible rate, and following the first Soviet atomic test (years before it was expected) in August 1949, President Harry S. Truman gave permission to proceed with the development of a whole new kind of nuclear weapon, the hydrogen bomb. Unlike an ordinary atomic bomb, no theoretical or even practical limit existed on the terrific energy released by the explosion of one of these new "thermonuclear" weapons. In 1957 the Soviet Union tested the world's first intercontinental ballistic missile (ICBM), and the United States soon followed suit. The potential warning each side might receive of an attack from the other was now reduced from hours to minutes. As a result of these and other technical advances, by the early 1960s political leaders on both sides had reached the conclusion that in any global nuclear war neither superpower could hope to escape unacceptable damage to its homeland.

This realization did not prevent the continuation of the nuclear arms race, however. Each side feared that a technological breakthrough by the other might yield an advantage sufficient to allow a preemptive "first strike" so powerful as to make retaliation impossible. To prevent this, each superpower had to secure its "second strike" capability, thus ensuring the continuation of the deterrent of "Mutual Assured Destruction" or MAD. To this end the United States constructed a "strategic nuclear triad" built around an enormous armada of intercontinental bombers, a force of approximately one thousand land-based ICBMs, and beginning in 1960, a fleet of submarines equipped with nuclear-tipped ballistic missiles. In the 1970s MAD was threatened by the creation by both sides of ICBMs that could deploy multiple warheads, each potentially capable of destroying an enemy missile while it was still in its hardened silo. Another potential threat to MAD was the advent of antiballistic missile (ABM) systems. Both sides had worked on these since the 1950s, but in recognition of the technical difficulty of "hitting a bullet with a bullet" and of the possibly destabilizing nature of a partially effective defense, in May 1972 the two superpowers signed the ABM Treaty, severely curtailing deployment of and future research on such systems. In the 1960s and especially the 1970s nuclear weapons had become so plentiful for both sides that they were deployed in large numbers in a tactical role as well. Relatively small ground units and even individual ships and aircraft were now potential targets of nuclear attack. This raised at least the realistic possibility for the first time in the Cold War of a successful defense of Western Europe against a Soviet ground assault.

The question remained, though, of just how many Europeans might be left after the radioactive smoke had cleared from such a "successful" defense. Advocates of a nuclear freeze swelled in number both in Europe and in the United States, and following the election of President Ronald Reagan in 1981, popular fears of nuclear war grew to a level not seen since the 1950s. Reagan also challenged the prevailing logic of MAD, renewing the ABM debate by calling in March 1983 for the creation of a vast new system of defense against nuclear attack through his "Strategic Defense Initiative" (derided by critics as "Star Wars"). This final round of the arms race was cut short, however, by the collapse of the Soviet economy in the 1980s and in 1991 of the Soviet Union itself.

In the years that followed the end of the Cold War nuclear fears, both public and governmental, rapidly switched from a general nuclear war to the possible acquisition of nuclear weapons by "rogue states," such as Iraq or North Korea, and whether or not to build a limited national missile defense system. After the attacks of 11 September 2001 on the Pentagon and the World Trade Center, nuclear terrorism became the greatest potential nightmare of all.

BIBLIOGRAPHY

Boyer, Paul. By the Bomb's Early Light: American Thought and Culture at the Dawn of the Atomic Age. Chapel Hill: University of North Carolina Press, 1994. First published in 1985.

Bundy, McGeorge. Danger and Survival: Choices about the Bomb in the First Fifty Years. New York: Random House, 1988. Thoughtful combination of history and memoir.

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nuclear weapons

The Columbia Encyclopedia, 6th ed.

Copyright The Columbia University Press

nuclear weapons, weapons of mass destruction powered by atomic, rather than chemical, processes. Nuclear weapons produce large explosions and hazardous radioactive byproducts by means of either nuclear fission or nuclear fusion. Nuclear weapons can be delivered by artillery, plane, ship, or ballistic missile (ICBM); some can also fit inside a suitcase. Tactical nuclear weapons can have the explosive power of a fraction of a kiloton (one kiloton equals 1,000 tons of TNT), while strategic nuclear weapons can produce thousands of kilotons of explosive force. After World War II, the proliferation of nuclear weapons became an increasing cause of concern throughout the world. At the end of the 20th cent. the vast majority of such weapons were held by the United States and the USSR; smaller numbers were held by Great Britain, France, China, India, and Pakistan. Israel also has nuclear weapons but has not confirmed that fact publicly; North Korea has conducted nuclear test explosions but probably does not have a readily deliverable nuclear weapon; and South Africa formerly had a small arsenal. Over a dozen other countries can, or soon could, make nuclear weapons. In addition to the danger of radioactive fallout, in the 1970s scientists began investigating the potential impact of nuclear war on the environment. The collective effects of the environmental damage that could result from a large number of nuclear explosions has been termed nuclear winter. Treaties have been signed limiting certain aspects of nuclear testing and development. Although the absolute numbers of nuclear warheads and delivery vehicles have declined since the end of the cold war, disarmament remains a distant goal. See atomic bomb; cold war; disarmament, nuclear; guided missile; hydrogen bomb; nuclear energy; nuclear physics.

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nuclear weapon

nuclear weapon Device whose enormous explosive force derives from the reactions of nuclear fission (splitting a heavy atomic nucleus in two) or fusion reactions (combining light atomic nuclei). In August 1945, the United States dropped the first atomic bombs on the Japanese cities of Hiroshima and Nagasaki. The bombs consisted of two stable, sub-critical masses of uranium or plutonium which, when brought forcefully together, caused the critical mass to be exceeded, thus initiating an uncontrolled nuclear chain reaction. In such detonations, huge amounts of energy and harmful radiation are released: the explosive force can be equivalent to 20,000 tonnes of TNT. The hydrogen bomb consists of an atomic bomb that on explosion provides a temperature high enough to cause nuclear fusion in a surrounding solid layer, usually lithium deuteride. The explosive power can be that of several million tonnes (megatons) of TNT. Devastation from such bombs covers a wide area: a 15-megaton bomb will cause all flammable material within 20km (12mi) to burst into flame. A third type of weapon, the neutron bomb, is a small hydrogen bomb, also called an enhanced radiation weapon, that produces a small blast but a very intense burst of high-speed neutrons. The lack of heat and blast means that buildings are not heavily damaged. The neutrons, however, produce intense radiation sickness in people located within a certain range, killing those affected within a week.

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